1. Field
The field generally includes computer graphics processing, and more specifically includes subject matter where a set of display points define a two dimensional representation of a straight line graphic object using three dimensional rasterization algorithms.
2. Background
Today, every aspect of computing, from creating animation to simple tasks such as word processing and e-mail, uses many graphics to create a more intuitive work environment for the user. Video adapters are graphic cards that plug into a personal computer to give the computer the capability to display graphical images. A video adapter that includes its own graphics processor is often called a graphics accelerator.
Because they contain their own memory and processor, graphics accelerators allow computers to display complex images faster on a display screen. A graphics accelerator achieves better results than the general-purpose central processing unit (CPU) used by a computer since its processor specializes in computing graphical transformations. In addition, a graphics accelerator frees up the computer's CPU to execute other commands while the graphics accelerator is handling graphics computations.
In the early days of computers, the graphics consisted of two dimensional images—points, lines, and squares that required only a two dimensional (2-D) graphics accelerator. The need to show depth and other attributes drove the development of three dimensional (3-D) graphics accelerators. Devices attached to a display screen typically include a 2-D graphics accelerator and a 3-D graphics accelerator, where the system switches between the two as needed. However, devices now in line to be sold on the market eliminate the 2-D graphics accelerator as a cost savings measure, leaving the 3-D graphics accelerator to perform all the tasks previously performed by the combination of the 2-D graphics accelerator and a 3-D graphics accelerator, including drawing lines.
Conventional lines drawn by a 3-D graphics accelerator typically are composed of two identical elongated triangles with one triangle positioned inverted and adjacent to the other at their bases to form a very long, thin rectangle. Sometimes referred to as triangle quad (quadrilaterals) lines, such straight lines find many uses. For example, the pull-down menus for word processing programs and internet web browser programs typically consist of text bounded by straight lines. The menu options displayed by a cell phone screen may include text bounded by and separated by straight lines. Angled straight lines have many graphical applications, such as to give depth to wire frame drawings of a house or a stack of shelves as presented on a device display screen.
For devices that employ a 3-D graphics accelerator to draw straight lines, the use of triangle quad lines creates problems when digitally representing analog line segments in screen space on a computer screen. For example, the two triangles that make-up the triangle quad line each have three vertices, for a total of six vertices. These six vertices require a lot of memory for storage and a lot of processing time to render all six vertices. A digitally represented triangle quad line may have a thickness where its corresponding analog line required no thickness. In addition, a great deal of processing time is dedicated to rasterizing pixels that will no be rendered as part of the triangle quad line. There is therefore a need in the art for an efficient technique to render a straight line segment utilizing an existing 3-D graphics accelerator.